• Remews — Geology of the Cape of Good Rope. 569 



jpolisliing powders and soaps. For all these pvirposes it would 

 require to be calcined and crushed. 



VI. — A Method of Facilitating Photography of Fossils, by 

 Gilbert van Ingen. 



A SIMPLE apparatus has been devised by which a fossil of 

 any size can be coated with a thin, opaque, white film 

 which effectually illuminates under the influence of both colour and 

 reflected light. The necessary articles for construction of the 

 apparatus are : a foot-blower, large wide-mouthed bottle of gallon 

 capacity, with three-holed rubber stopper, two bottles of quart 

 capacity, each with two-holed rubber stopper, glass tubing of one- 

 eighth-inch bore and rubber tubing to fit same (three feet of each), 

 two U-shaped calcium chloride tubes filled with chloride, strong 

 ammonia water, strong HCl. To use: Air from the foot-blower 

 is forced into the large bottle, which equalises the pressure, and 

 thence through the ammonia water and HCl into the smaller bottles. 

 The air, mixed with the gases taken up, is passed through the calcium 

 chloride tubes, where the moisture is extracted, and escapes through 

 the two glass tubes held in the hands at a short distance from the 

 object to be coated. The union of the two gases escaping from 

 the tubes forms ammonium chloride, which settles as an exceedingly 

 fine powder upon the surface of the specimens. The coating thus 

 obtained, when deposited slowly, is of a dead white, which effectually 

 hides all coloration of the surface, and, instead of obliterating the 

 .finer modelling, renders the details of the topography with the 

 utmost distinctness. Some surfaces take the coating more readily 

 than others. Fine-grained black limestones and all other rocks 

 that present a velvety surface take the coating well. Porous rocks 

 are difficult to cover. Specimens which have been handled must 

 be washed with benzene. The coating of the salt is perfectly 

 -harmless, and may readily be removed by water, gentle heating, 

 or the use of a soft brush. Photographs of such coated specimens 

 fulfil more nearly the requirements of the work than do those taken 

 by the ordinary methods. The coating is also of great assistance 

 in the elucidation of the details of small species, as was found to 

 advantage while studying the lobation of the heads of small trilobites. — 

 Annals N.Y. Acad. ScL, xiv, pp. 115, 116 ; March, 1902. 



I^ IE "V" I E "V^ S. 



I. — Annual Eeports of the Geological Commission of the 



Cape of Good Hope for the Years 1901 and 1902. 

 rnHESE two volumes, issued by the Department of Agriculture of 

 X the Cape of Good Hope, reach the same standard of excellence 

 as previous publications, both with respect to the style in which they 

 are presented and the important and interesting matter they contain. 

 Since the last Keport the Scientific staff has undergone some 

 change. Dr. G. S. Corstorphine retired from the Directorship in 

 1901, and was succeeded by Mr. A. W. Rogers under the title of 



